Method for calculation of initial and maximum reaction rates, Michaelis constant, and determination of the kind of inhibition

Sulphuric acid (H2SO4) is one of the most produced chemicals in the world. The critical step of the sulphuric acid production is the oxidation of sulphur dioxide (SO2) to sulphur trioxide (SO3) which takes place in a multi catalytic bed reactor. In this study, a representative kinetic rate equation was rigorously selected to develop a mathematical model to perform the multi-objective optimization (MOO) of the reactor. The objectives of the MOO were the SO2 conversion, SO3 productivity, and catalyst weight, whereas the decisions variables were the inlet temperature and the length of each catalytic bed. MOO studies were performed for various design scenarios involving a variable number of catalytic beds and different reactor configurations. The MOO process was mainly comprised of two steps: (1) the determination of Pareto domain via the determination a large number of non-dominated solutions, and (2) the ranking of the Pareto-optimal solutions based on preferences of a decision maker. Results show that a reactor comprised of four catalytic beds with an intermediate absorption column provides higher SO2 conversion, marginally superior to four catalytic beds without an intermediate SO3 absorption column. Both scenarios are close to the ideal optimum, where the reactor temperature would be adjusted to always be at the maximum reaction rate. Results clearly highlight the compromise existing between conversion, productivity and catalyst weight.

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Probing Dense QCD Matter: Muon Measurements with the CBM Experiment at FAIR

Particles ◽

10.3390/particles4020019 ◽

2021 ◽

Vol 4 (2) ◽

pp. 205-213

Author(s):

Anna Senger ◽

Peter Senger

Keyword(s):

Performance Studies ◽

Reaction Rates ◽

High Density ◽

Streaming Data ◽

Qcd Phase Diagram ◽

Chemical Potentials ◽

Muon Pairs ◽

Caloric Curve ◽

Density Equation

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt is designed to investigate the properties of high-density QCD matter with multi-differential measurements of hadrons and leptons, including rare probes such as multi-strange anti-hyperons and charmed particles. The research program covers the study of the high-density equation-of-state of nuclear matter and the exploration of the QCD phase diagram at large baryon chemical potentials, including the search for quark matter and the critical endpoint of a hypothetical 1st order phase transition. The CBM setup comprises detector systems for the identification of charged hadrons, electrons, and muons; for the determination of collision centrality and the orientation of the reaction plane; and a free-streaming data read-out and acquisition system, which allows online reconstruction and selection of events up to reaction rates of 10 MHz. In this article, emphasis is placed on the measurement of muon pairs in Au-Au collisions at FAIR beam energies, which are unique probes used to determine the temperature of the fireball, and hence to search for a caloric curve of QCD matter. Simultaneously, the subthreshold production of charmonium can be studied via its dimuon decay in order to shed light on the microscopic structure of QCD matter at high baryon densities. The CBM setup with focus on dimuon measurements and the results of the corresponding physics performance studies will be presented.

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Determination of the intrinsic Michaelis constant of immobilized alpha-chymotrypsin.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)46677-4 ◽

1993 ◽

Vol 268 (25) ◽

pp. 18637-18639

Author(s):

S. Blais ◽

R. Lortie

Keyword(s):

Michaelis Constant

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A Novel Sucrose Isomerase Producing Isomaltulose from Raoultella terrigena

Applied Sciences ◽

10.3390/app11125521 ◽

2021 ◽

Vol 11 (12) ◽

pp. 5521

Author(s):

Li Liu ◽

Shuhuai Yu ◽

Wei Zhao

Keyword(s):

Ph Value ◽

Wild Type ◽

Michaelis Constant ◽

Wild Type Enzyme ◽

Maximum Reaction Rate ◽

E Coli ◽

Maximum Reaction ◽

Conversion Rates ◽

Raoultella Terrigena ◽

Sucrose Isomerase

Isomaltulose is widely used in the food industry as a substitute for sucrose owing to its good processing characteristics and physicochemical properties, which is usually synthesized by sucrose isomerase (SIase) with sucrose as substrate. In this study, a gene pal-2 from Raoultella terrigena was predicted to produce SIase, which was subcloned into pET-28a (+) and transformed to the E. coli system. The purified recombinant SIase Pal-2 was characterized in detail. The enzyme is a monomeric protein with a molecular weight of approximately 70 kDa, showing an optimal temperature of 40 °C and optimal pH value of 5.5. The Michaelis constant (Km) and maximum reaction rate (Vmax) are 62.9 mmol/L and 286.4 U/mg, respectively. The conversion rate of isomaltulose reached the maximum of 81.7% after 6 h with 400 g/L sucrose as the substrate and 25 U/mg sucrose of SIase. Moreover, eight site-directed variants were designed and generated. Compared with the wild-type enzyme, the enzyme activities of two mutants N498P and Q275R were increased by 89.2% and 42.2%, respectively, and the isomaltulose conversion rates of three mutants (Y246L, H287R, and H481P) were improved to 89.1%, 90.7%, and 92.4%, respectively. The work identified a novel SIase from the Raoultella genus and its mutants showed a potential to be used for the production of isomaltulose in the industry.

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